Structure and method of reticle pod having inspection window

ABSTRACT

A method includes: inspecting a reticle in a reticle pod, the reticle pod including a sealed space to accommodate the reticle, and the reticle pod further comprising a window arranged on an upper surface of the reticle pod, wherein the inspecting is performed through the window; and moving the reticle out of the reticle pod for performing a lithography operation using the reticle.

PRIORITY CLAIM AND CROSS-REFERENCE

This application is a continuation application of a U.S. non-provisionalapplication Ser. No. 17/728,734 filed, Apr. 25, 2022, which is acontinuation application of U.S. non-provisional application Ser. No.16/732,204 filed Dec. 31, 2019, now U.S. Pat. No. 11,314,164 B2, thedisclosures of which are hereby incorporated by reference in itsentirety.

BACKGROUND

Reticles are fabricated to form circuit patterns thereon and used totransfer the circuit patterns to wafers in a semiconductor manufacturingprocess. The fidelity and integrity of the reticle patterns are crucialto the success of mass production of the wafers and thus many techniquesare proposed to fabricate the reticle and protect the reticle patternsfrom damage or contamination. A reticle pod is usually employed tohouse, protect and transport the reticles in modern semiconductormanufacturing processes.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It shouldbe noted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a schematic cross-sectional view of a reticle pod, inaccordance with some embodiments.

FIGS. 2A and 2B are schematic plan views of the reticle pod in FIG. 1 ,in accordance with some embodiments.

FIGS. 3A to 3L are schematic cross-sectional views of intermediatestages of a method of manufacturing a reticle, in accordance with someembodiments.

FIGS. 4A to 4E are schematic cross-sectional views of intermediatestages of a method of repairing a reticle, in accordance with someembodiments.

FIGS. 5A to 5E are schematic cross-sectional views of intermediatestages of a method of repairing a reticle, in accordance with someembodiments.

FIGS. 6A to 6E are schematic cross-sectional views of intermediatestages of a method of repairing a reticle, in accordance with someembodiments.

FIG. 7 is a flowchart of a method of manufacturing a reticle, inaccordance with some embodiments.

FIG. 8 is a flowchart of a method of manufacturing a semiconductordevice, in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 70 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the disclosure are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the deviation normally found in therespective testing measurements. Also, as used herein, the terms“about,” “substantial” and “substantially” generally mean within 10%,5%, 1% or 0.5% of a given value or range. Alternatively, the terms“about,” “substantial” and “substantially” mean within an acceptablestandard error of the mean when considered by one of ordinary skill inthe art. Other than in the operating/working examples, or unlessotherwise expressly specified, all of the numerical ranges, amounts,values and percentages such as those for quantities of materials,durations of times, temperatures, operating conditions, ratios ofamounts, and the likes thereof disclosed herein should be understood asmodified in all instances by the terms “about,” “substantial” or“substantially.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the present disclosure and attachedclaims are approximations that can vary as desired. At the very least,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques. Ranges can be expressed herein as being from one endpoint toanother endpoint or between two endpoints. All ranges disclosed hereinare inclusive of the endpoints, unless specified otherwise.

Embodiments of the present disclosure discuss structures and operatingmethods of a reticle pod. Embodiments of the present disclosure alsodiscuss methods of manufacturing and repairing a reticle. The reticlepod generally includes a base and a cover that form a sealed space foraccommodating the reticle. The proposed reticle pod features a window inthe cover, wherein the window allows early detection of pattern defectsduring a manufacturing process of the reticle. Inspection operations maybe performed immediately after a certain manufacturing step is performedin order to inspect whether a defect occurs due to this manufacturingstep. The defect detection can therefore be performed in timely and moreprecise manners, and an early repair can be achieved accordingly.

Throughout the present disclosure, the terms “reticle,” “photomaskreticle” and “mask” may be used interchangeably to refer to a deviceused in a photolithography operation, in which an opaque image accordingto a circuit pattern is formed on a substrate plate. The substrate platemay be transparent. The image of the circuit pattern on the reticle istransferred to a substrate or a wafer through a radiation source of thephotolithography operation. Radiation from the radiation source mayimpinge on the substrate via the reticle in a transmissive or reflectivemanner.

FIG. 1 is a schematic cross-sectional view of a reticle pod 10, inaccordance with some embodiments. The reticle pod 10 is used toaccommodate a reticle 108. In some embodiments, the reticle 108 is atransmissive-type reticle, a reflective-type reticle, or anothersuitable type of reticle. The reticle pod 10 includes a base 110 and acover 120 over the base 110. The cover 120 is detachably coupled to thebase 110 for forming a closed space in which the reticle 108 is secured.

FIGS. 2A and 2B are schematic plan views of the base 110 and the cover120, respectively, of the reticle pod 10 in FIG. 1 , in accordance withsome embodiments. The cross-sectional view of FIG. 1 is taken along thesectional lines AA in FIGS. 2A and 2B. Referring to FIG. 1 and FIG. 2A,the base 110 includes a platform 102, reticle holders 104 and latches106. In some embodiments, the platform 102 is used to support thereticle 108 through the reticle holder 104. The platform 102 may beformed of PEEK (polyether ether ketone), PMMA (polymethyl methacrylate),or other suitable materials. The platform 102 may include a circular orquadrilateral shape, such as a rectangular or square shape. In someembodiments, the reticle 108 has a diameter or width W1 between about 14cm and about 16 cm, such as 15 cm. In some embodiments, the platform 102has a width W2 between about 22 cm and about 30 cm. In some embodiments,the width W2 of the platform 102 is between about 150% and about 200% ofthe width W1 of the reticle 108.

In some embodiments, the reticle holders 104 are used to support thereticle 108 such that the reticle is suspended above the platform 102 bya distance. In some embodiments, the reticle holders 104 are formed ofPEEK, PMMA or other suitable materials. Referring to FIG. 2A, thereticle holders 104 may be disposed around the corners of the reticle108 from a top-view perspective. For example, two reticle holders 104are disposed closely adjacent to a corner of the reticle 108. Referringto FIG. 1 , each of the reticle holders 104 may include a recess 104Rthat is adjacent to an upper surface from a cross-sectional view and maybe configured to receive the reticle 108. In some other embodiments, therecess 104R of the reticle holders 104 is replaced with a chamfer thatfaces the reticle 108 and is configured to receive the reticle 108.

The latches 106 are used to couple the base 110 to the cover 120. Insome embodiments, the cover 120 includes slots (not shown) correspondingto the latches 106 for coupling to the base 110. The latches 106 may beimplemented by mechanical or electronic latching members, as known inthe art. Through the latches 106, a closed space is formed by the base110 and the cover 120 to retain and secure the reticle 108.

Referring to FIG. 1 and FIG. 2B, the cover 120 detachably houses thebase 110 and is configured to cover the reticle 108 from above. Thecover 120 includes a frame 112 and a window 114. The frame 112constitutes the body of the cover 120 and provides physical support andmechanical strength to the cover 120.

The frame 112 may have various configurations depending on therequirements. For example, the frame 112 has a stepped shape from across-sectional view in which a central part 112C is higher than aperipheral part 112P surrounding the central part. In some embodiments,the cover 120 or the frame 112 has a height between about 5 cm and about8 cm. The frame 112 may be formed of electrically insulating materials,e.g., a plastic or polymer material. In some embodiments, the frame 112includes PEEK or PMMA. In some embodiments, the frame 112 is formed ofopaque materials.

The window 114 is arranged in the central part 120C of the cover 120that is higher than the peripheral part 120P of the cover 120. The frame112 may include an opening in the central part 120C for accommodatingthe window 114 therein. The window 114 may be laterally surrounded bythe frame 112. In some embodiments, the frame 112 includes support beams117 around the corners of the window 114. The support beam 117 may forma right triangle with the sides of the window 114 to which the supportbeam 117 connects, wherein the support beam 117 serves as the hypotenuseof the triangle and supports the window 114 from the bottom of thewindow 114.

The reticle 108 includes circuit patterns on an upper side facing thewindow 114. The base 110 and the frame 112 are generally formed ofopaque materials. Therefore, the window 114 allows manual or machineinspection of the reticle 108 when the reticle pod 10 is in a closedstate. The window 114 may be formed of a window body 116 and films 118coated on the window body 116. In some embodiments, the window 114includes transparent materials. During an inspection operation, aradiation from a radiation source RS, e.g., a laser beam, may be emittedto impinge on the reticle 108. A patterned radiation reflected from thereticle 108 carries geometries of the circuit pattern on the reticle108. A comparison of the reflected laser beam pattern with an originalpattern can aid in detecting the defects in the circuit pattern, such asforeign contaminant, particles, protrusion, material loss (intrusion),excess material (extension or bridging), necking and pinholes. In someembodiments, the window 114 allows the radiation from the radiationsource RS to pass through such that the radiation does not react with aphotoresist material of the reticle 108. In some embodiments, the window114 allows the radiation having a wavelength in the range of green lightto pass through, wherein the wavelength of the radiation is betweenabout 400 nanometers (nm) and about 700 nm. In some embodiments, theradiation has a wavelength between about 500 nm and about 560 nm. If aradiation at a wavelength greater than about 700 nm is used as aninspection radiation, the energy of the reflected light beam may beinsufficient for accurately conveying the circuit pattern of the reticle108. If a radiation at a wavelength less than about 400 nm is used as aninspection radiation, the energy of the inspection radiation may causedamage or unexpected reaction of the materials in the reticle 108, e.g.,the photoresist material in the reticle 108 may react to the radiationin a manner that leads to property change.

In some embodiments, the window 114 has a quadrilateral shape, such as arectangular or square shape. The window 114 is aligned with the reticle108 when the reticle 108 is disposed in the reticle pod 10. In someembodiments, the window 114 covers the entire reticle 108 when thereticle 108 is disposed in the reticle pod 10 such that the radiationcan be projected onto the entire upper surface of the reticle 108 andreflect back to a detection circuit through the window 114. In someembodiments, the window 114 covers an entirety of a pattern area withinwhich the circuit pattern of the reticle 108 is formed. The window 114may have a width W3 which is greater than or substantially equal to thewidth W1 of the reticle 108. In some embodiments, the width W3 isbetween about 15 cm and about 30 cm, or between about 18.75 cm and about26.25 cm. In some embodiments, the width W3 is between about 125% andabout 175% of the width W1 of the reticle 108. In some embodiments, thewindow 114 has an area between about 120% and about 250% of the area ofthe reticle 108.

In some embodiments, the window body 116 has a thickness between about0.05 cm and about 1 cm. In some embodiments, the window body 116 may beformed of a transparent material, such as glass. The window body 116 mayinclude fused silica (SiO₂), fused quartz, calcium fluoride (CaF₂),silicon oxide-titanium oxide alloy, sapphire or other suitable materialsfree of defects. In some embodiments, the window body 116 has atransmittance of greater than about 70%, greater than about 80%, orgreater than about 90%, with respect to an inspection radiation.

In some embodiments, the films 118 are coated on both the outer surface(film 118A) and the inner surface (film 118B) of the window body 116,where the film 118A faces upward and the film 118B faces downward (i.e.,facing the base 110). The films 118 may be coated on the window body 116using physical vapor deposition (PVD), chemical vapor deposition (CVD),atomic layer deposition (ALD) or another suitable deposition process.The films 118 may improve the inspection efficiency and protection ofthe reticle 108. In some embodiments, the film 118 has a transmittanceof greater than about 65%, greater than about 70%, or greater than about80%, with respect to an inspection radiation. Furthermore, the films 118may facilitate removal of electrostatic charges generated duringtransport of or contact with the reticle pod 10, and therefore damagedue to electrostatic discharge of the reticle 108 or accumulation ofcontaminating particles resulting from the electrostatic charges can bereduced or eliminated. In some embodiments, the films 118 are conductivefilms and include a conductive material, such as aluminum zinc oxide(AZO), indium tungsten oxide (ITO), fluorine doped tin oxide (FTO),carbon nanotube or a combination thereof, for conducting electrostaticcharges.

In some embodiments, the film 118A or 118B has a deposition thickness T,measured through the surface of one side of the window body 116, betweenabout 20 nm and about 200 nm. The film 118A or 118B having a thicknessless than about 20 nm may not provide sufficient capability ofconducting electrostatic charges. The film 118A or 118B having athickness greater than about 200 nm may not provide sufficienttransmittance for the inspection radiation of interest. In someembodiments, the thickness of the film 118A or 118B is reduced if theinspection radiation has a greater wavelength. In some embodiments, thefilm 118 formed of AZO includes a thickness of about 20 nm with respectto an inspection radiation at a wavelength between 400 nm and about 700nm. In some embodiments, the film 118 formed of ITO includes a thicknessbetween about 20 nm and about 100 nm with respect to an inspectionradiation at a wavelength between about 400 nm and about 500 nm. In someembodiments, the film 118 formed of ITO includes a thickness of betweenabout 90 nm and about 110 nm, such as 100 nm, with respect to aninspection radiation at a wavelength between about 500 nm and about 600nm. In some embodiments, the film 118 formed of ITO includes a thicknessbetween about 100 nm and about 200 nm with respect to an inspectionradiation at a wavelength between about 600 nm and about 700 nm.

In some embodiments, the inspection operation is performed under anatmosphere pressure. Although the chances of contamination at theatmosphere pressure may be higher than that at a vacuum environment, thereticle 108 can still be well protected by the reticle pod 10 during theinspection operation since the reticle 108 is inspected within thesealed reticle pod 10. The inspection radiation can be emitted to thepattern of the reticle 108 through the window 114 without exposing thereticle 108 to the outside of the reticle pod 10, the likelihood ofcontamination can be reduced.

FIGS. 3A to 3L are schematic cross-sectional views of intermediatestages of a method of manufacturing the reticle 108, in accordance withsome embodiments. The reticle 108 may be categorized as a transmissivetype, a reflective type, or another suitable type. In the depictedexample, a transmissive-type reticle 108 is illustrated. It isunderstood that additional operations can be provided before, during,and after processes shown in FIGS. 3A to 3L, and some of the operationsdescribed below can be replaced or eliminated for additional embodimentsof the method. The order of the operations may be interchangeable.Further, the same or similar configuration, structure, materials,operations or processes of the foregoing embodiments may be employed inthis embodiment and the detailed explanation may be omitted.

Referring to FIG. 3A, the reticle 108 is received or provided andincludes a stack of a substrate 302, a phase shift layer 304, ashielding layer 306, a mask layer 308 and a photoresist layer 310 overone another. It is understood that other layers may be optionally addedto the stack of the reticle 108.

In some embodiments, the substrate 302 is configured to allowphotolithography radiation to pass through. The substrate 302 may be alow temperature expansion material (LTEM). In some embodiments, thesubstrate 302 is a transparent material and may be formed of fusedsilica, fused quartz, calcium fluoride (CaF₂), silicon carbide, siliconoxide-titanium oxide alloy and/or other suitable LTEM.

In some embodiments, the phase shift layer 304 is configured to changeor shift the phase of the incident radiation that passes through inorder to improve the image sharpness. In some embodiments, the phaseshift layer 304 includes molybdenum-silicon nitride (MoSiN),molybdenum-silicide (MoSi), molybdenum-silicon oxynitride (MoSiON),titanium nitride, titanium silicon nitride, silicon nitride, or othersuitable materials.

In some embodiments, the shielding layer 306 is configured to absorbundesired portions of incident photolithography radiation for forming apatterned lithography radiation on a workpiece. In some embodiments, theshielding layer 306 includes chromium or a compound thereof, such asCrN, CrON, and CrO. In some embodiments, the shielding layer 306includes molybdenum or a compound thereof, such as MoSi, MoSiN, andMoSiON. In some embodiments, the shielding layer 306 includes tantalumor a compound thereof, such as TaN, TaON, TaB, TaBN, TaHfN, TaHf, TaSi,TaSiN, TaGe, TaGeN, TaZrN, and TaZr.

In some embodiments, the mask layer 308 includes silicon oxide, siliconnitride, silicon oxynitride, silicon carbide, or other maskingmaterials. In some embodiments, the photoresist layer 310 includes aphotosensitive material that serves as a positive-tone photoresist or anegative-tone photoresist.

Each of the phase shift layer 304, the shielding layer 306, the masklayer 308 and the photoresist layer 310 may be deposited over thesubstrate 302 by PVD, CVD, ALD, spin coating, or another suitabledeposition technique.

Still referring to FIG. 3A, an exposure operation is performed on thephotoresist layer 310 to transfer a predetermined circuit pattern to thephotoresist layer 310. Portions 312 of the photoresist layer 310corresponding to the circuit pattern are exposed accordingly. Theportions 312 may be exposed using an electron-beam (e-beam) writer. Thee-beam writer generates a geometrically constrained stream of electronsthat irradiate selected areas of the photoresist layer 310. One ofordinary skill in the art will recognize that any other suitable writermay be used for irradiating selected areas of the photoresist layer 310.In the case of a positive-tone photoresist layer 310, the irradiatedareas are made soluble in the developer and the non-irradiated areasremain insoluble in the developer.

In some embodiments, a post-exposure bake operation is performed toenhance the exposure performance and causes the exposed portions 312 toextend through the thickness of the photoresist layer 310.

Referring to FIG. 3B, a development operation is performed to remove theexposed portions 312 using a developer. Trenches 314 are formed in thephotoresist layer 310 and expose an upper surface of the mask layer 308.The developer may be a positive-tone developer or a negative-tonedeveloper. Therefore, a patterned photoresist layer 310P is formed.

Subsequently, the mask layer 308 is etched as shown in FIG. 3C. The masklayer 308 is etched using a dry etch, a wet etch or a combinationthereof, using the patterned photoresist layer 310P as an etch mask andstopping at the shielding layer 306. As a result, a patterned mask layer308P is formed such that the circuit pattern is transferred thereto fromthe patterned photoresist layer 310P.

FIG. 3D illustrates the stripping of the patterned photoresist layer310P once the patterned mask layer 308P is formed. The patternedphotoresist layer 310P may be stripped using a dry etch, a wet etch, alaser etch, a combination thereof, or another suitable strippingoperation.

FIG. 3E shows the subsequent forming of a patterned shielding layer306P. The forming of the patterned shielding layer 306P is performed byetching the shielding layer 306 using the mask layer 308 as an etchmask. As a result, the trenches 316 extend through the shielding layer306 and stop at the phase shift layer 304. An upper surface of the phaseshift layer 304 is therefore exposed. In some embodiments, the circuitpattern is transferred to the patterned shielding layer 306P. Theetching of the patterned shielding layer 306P may be performed using adry etch, a wet etch or a combination thereof.

FIG. 3F illustrates the removal of the patterned mask layer 308P oncethe patterned shielding layer 306P is formed. The patterned mask layer308P may be removed using a dry etch, a wet etch, a laser etch, oranother suitable stripping operation. Trenches 318 in the patternedshielding layer 306P that correspond to the trenches 316 and representthe circuit pattern remain in place after the removal operation.

FIG. 3G shows the subsequent patterning of the phase shift layer 304 toform a patterned phase shift layer 304P. The patterning of the phaseshift layer 304 is performing by etching the phase shift layer 304 usingthe patterned shielding layer 306P as an etch mask. As a result, thetrenches 318 extend through the phase shift layer 304 and stop at thesubstrate 302. An upper surface of the substrate 302 is thereforeexposed. In some embodiments, the circuit pattern is transferred to thepatterned phase shift layer 304P. The patterned phase shift layer 304Pis formed using a dry etch, a wet etch or a combination thereof.

Referring to FIG. 3H, a second photoresist layer 320 is deposited overthe patterned shielding layer 306P and the patterned phase shift layer304P. The second photoresist layer 320 may cover the patterned shieldinglayer 306P and may fill the trenches 318. In some embodiments, thesecond photoresist layer 320 includes a photosensitive material and mayuse a material the same as or different from that of the photoresistlayer 310.

Still referring to FIG. 3I, an exposure operation is performed on thesecond photoresist layer 320 to transfer a second pattern to the secondphotoresist layer 320. Portions 322 in the second photoresist layer 320corresponding to the second pattern are exposed accordingly. Theportions 322 may be exposed using an electron-beam (e-beam) writer orany other suitable writer for irradiating selected areas of the secondphotoresist layer 320.

Referring to FIG. 3J, a development operation is performed to remove theexposed portions 322. A recess 324 is formed in the second photoresistlayer 320, wherein the recess 324 re-opens the trenches 318 and maypartially expose the upper surface of the patterned shielding layer306P. Therefore, a patterned second photoresist layer 320P is formed.The development operation may be performed using a developer that servesas a positive-tone developer or a negative-tone developer.

Subsequently, the patterned shielding layer 306P is etched to form thesecond pattern in an additionally-patterned shielding layer 306F, asshown in FIG. 3K. The patterned shielding layer 306P is etched using adry etch, a wet etch or a combination thereof, using the patternedsecond photoresist layer 320P as an etch mask. Therefore, theadditionally-patterned shielding layer 306F is formed. Trenches 326corresponding to the trenches 318 are formed in the patterned phaseshift layer 304P. The patterned phase shift layer 304P is keptsubstantially intact during the patterning operation of theadditionally-patterned shielding layer 306F.

FIG. 3L illustrates the stripping of the patterned second photoresistlayer 320P after the additionally-patterned shielding layer 306F isformed. The patterned second photoresist layer 320P may be strippedusing a dry etch, a wet etch, a laser etch, or another suitablestripping operation. In some embodiments, the second pattern in thepatterned phase shift layer 304P increases the sharpness of the image ofthe additionally-patterned shielding layer 306F that is to be projectedonto the reticle 108.

As discussed previously, the reticle pod 10 that includes the cover 120having the window 114 enables early detection for reticle manufacturersin any intermediate stage of the manufacturing procedure, in which thereticle pod 10 is moved out of the manufacturing tool and subjected tothe inspection operation with the reticle 108 being kept sealed withinthe reticle pod 10. Since there is no need to remove the reticle 108 outof the reticle pod 10 and to expose the reticle 108 to an atmospherepressure environment of the inspection operation, the likelihood ofcontamination is reduced. Further, the reticle defects can be detectedand repaired in an earlier stage.

FIGS. 4A to 4E are schematic cross-sectional views of intermediatestages of a method of repairing the reticle 108, in accordance with someembodiments. FIG. 4A shows a schematic cross-sectional view of thereticle 108 immediately after the development operation for forming thepatterned photoresist layer 310P with reference to FIG. 3B. A foreignparticle P over a left-side trench 314 is detected during the inspectionoperation. The inspection may be executed across the upper surface ofthe reticle 108 and FIG. 4A is shown for illustrational purposes. Thisdetected particle P may imply that a processing tool having processingchambers for performing the development operation or precedingoperations is contaminated. A cleaning operation may be required beforethe processing tool is operated on the next reticle. The cleaningoperation may include a purge step using a purge gas pulse comprising aninert gas, such as nitrogen (N₂), helium (He), neon (Ne), argon (Ar),krypton (Kr), xenon (Xe), or radon (Rn). In some embodiments, thecleaning operation includes evacuation of the processing chamber toremove unreacted oxygen-containing gas, unreacted metal-containing gas,and any byproducts from the processing chamber. The early detection ofthe contamination location aids in accurately identifying thecontaminated processing tool in the processing system and thereforesaves time and cost.

FIG. 4B illustrates a schematic cross-sectional view of the reticle 108immediately after the patterning operation of the mask layer 308 withreference to FIG. 3C. The particle P may not be detected or cleared atthe time before the patterning of the mask layer 308. As a result, theetchant of the patterning operation is obstructed by the particle P andfails to reach the left-side trench 314. A defective patterned masklayer 308D is formed accordingly. FIG. 4C illustrates a schematiccross-sectional view of the reticle 108 immediately after the strippingoperation of the patterned photoresist layer 310P with reference to FIG.3D. The left-side trench 316 that would otherwise be created in acontamination-free patterning operation is missing due to the particle Pand instead there is an excess portion 316M of the defective patternedmask layer 308D.

FIG. 4D illustrates a schematic repairing operation in accordance withsome embodiments. A repairing radiation beam RB, which may be a laserbeam or an electron beam (e-beam), is used to remove or etch the excessportion 316M of the defective patterned mask layer 308D. The radiationbeam RB may be properly controlled in power and radiation profile to fitthe geometries of the portion 316M without adversely affecting theremaining portions of the defective patterned mask layer 308D. In someembodiments, an etching gas RG is introduced during the repairingoperation. The etching gas aids in the removal of the excess portion316M together with the application of the radiation beam RB. In someembodiments, the etching gas RG with respect to the defective patternedmask layer 308D may include a fluorine-based gas, such as F₂, CF₄, SF₆,SnF₄, XeF₂, or another suitable gas such as I₂.

FIG. 4E shows a schematic cross-sectional view of a repaired reticle108, in accordance with some embodiments. As shown in FIG. 4E, thecircuit pattern of the patterned mask layer 308P is correctly restoredto match that of the successfully fabricated reticle 108 shown in FIG.3D.

FIGS. 5A to 5E are schematic cross-sectional views of intermediatestages of a method of repairing the reticle 108, in accordance with someembodiments. FIG. 5A shows a schematic cross-sectional view of thereticle 108 immediately after the development operation for forming thepatterned photoresist layer 310P with reference to FIG. 3B. A defectivepatterned photoresist layer 310D is detected, wherein a portion 310M(referred to as an intrusion) is erroneously removed during thedevelopment operation. This may imply that the design, such as therecipe parameters of the operation for forming the patterned photoresistlayer 310P, contain errors, or the materials of the photoresist layer310 are degraded. In some embodiments, a material rebuilding operationmay be performed for repairing the portion 310M. The early detection ofthe location of the defective portion aids in accurately identifying theproblematic design during the processing procedure. The materialrebuilding operation may be introduced in the current or subsequentsteps by taking into account the processing time and cost of eachoption. In some embodiments, the defective patterned photoresist layer310D is stripped in a repairing operation. Subsequently, a series ofdeposition, exposure, and development operations are applied anew toform a defect-free patterned photoresist layer 310P over the mask layer308, and the manufacturing procedure continues with the step withreference to FIG. 3C.

FIG. 5B illustrates a schematic cross-sectional view of the reticle 108immediately after the patterning operation of the patterned mask layer308P with reference to FIG. 3C. In some embodiments, the defectivepatterned photoresist layer 310D is not repaired before the patterningof the mask layer 308. As a result, the etchant for patterning the masklayer 308 etches a portion 308M, in addition to forming the trenches314, due to the absence of the portion 310M. A defective patterned masklayer 308D is formed accordingly. FIG. 5C illustrates a schematiccross-sectional view of the reticle 108 immediately after the strippingoperation of the patterned photoresist layer 310P with reference to FIG.3D. The portion 308M that would be otherwise formed in place in adefect-free patterning operation is missing.

FIG. 5D illustrates a schematic repairing operation in accordance withsome embodiments. A repairing radiation beam RB, which may be a laserbeam or an electron beam (e-beam), is used to rebuild the portion 308Mof the defective patterned mask layer 308D. The radiation beam RB may beproperly controlled in power and radiation profile to fit the geometriesof the portion 308M without adversely affecting the remaining portionsof the defective patterned mask layer 308D or the underlying shieldinglayer 306. In some embodiments, a reacting gas RG is introduced duringthe repairing operation. The reacting gas RG aids in the formation ofthe portion 308M together with the application of the radiation beam RB.In some embodiments, the reacting gas RG with respect to the defectivepatterned mask layer 308D may include a silicon-based material, such as(CH₃O)₄Si, (C₂H₅O)₄Si, (CH₄SiO)₄, (CH₄SiO)₅, or another suitablematerial.

FIG. 5E shows a schematic cross-sectional view of a repaired reticle108, in accordance with some embodiments. As shown in FIG. 5E, thecircuit pattern of the patterned mask layer 308P is correctly restoredto match that of the successfully fabricated reticle 108 in FIG. 3D.

FIGS. 6A to 6E are schematic cross-sectional views of intermediatestages of a method of repairing the reticle 108, in accordance with someembodiments. The method illustrated in FIGS. 6A to 6E addresses adetection scenario similar to that illustrated in FIGS. 5A to 5E, butadopts a different approach. FIG. 6A shows a schematic cross-sectionalview of the reticle 108 similar to that shown in FIG. 5C, in which adefective patterned mask layer 308D is detected. The portion 310M, whichshould otherwise exist, is erroneously removed during the developmentoperation.

FIG. 6B illustrates a schematic cross-sectional view of the reticle 108immediately after the patterning operation of the shielding layer 306with reference to FIG. 3E. In some embodiments, the defective patternedphotoresist layer 310D and the defective patterned mask layer 308D arenot repaired before the patterning of the shielding layer 306. As aresult, the etchant for patterning the shielding layer 306 erroneouslyetches a portion 306M, in addition to forming the trenches 318, due tothe absence of the portions 310M and 308M as etch masks. A defectivepatterned shielding layer 306D is formed accordingly. FIG. 6Cillustrates a schematic cross-sectional view of the reticle 108immediately after the stripping operation of the patterned mask layer308P with reference to FIG. 3F. The portion 306M that would be otherwiseformed in place in a defect-free patterning operation is missing.

FIG. 6D illustrates a schematic repairing operation in accordance withsome embodiments. A repairing radiation beam RB, which may be a laserbeam or an electron beam (e-beam), is used to rebuild the portion 306Mof the defective patterned shielding layer 306D. The radiation beam RBmay be properly controlled in power and radiation profile to fit thegeometries of the portion 306M without adversely affecting the remainingportions of the defective patterned shielding layer 306D or theunderlying phase shift layer 304. In some embodiments, a reacting gas RGis introduced during the repairing operation. The reacting gas RG aidsin the formation of the portion 306M together with the application ofthe radiation beam RB. In some embodiments, the reacting gas RG withrespect to the patterned shielding layer 306P may include achlorine-based gas, such as Cl₂, SnCl₄, NOCl, NO₂Cl, CCl₄, or anothersuitable gas.

FIG. 6E shows a schematic cross-sectional view of a repaired reticle108, in accordance with some embodiments. As shown in FIG. 6E, thecircuit pattern of the patterned shielding layer 306P is correctlyrestored to match that of the successfully fabricated reticle 108 inFIG. 3F.

FIG. 7 is a flowchart of a method 70 of manufacturing a reticle, inaccordance with some embodiments. It is understood that additionaloperations can be provided before, during, and after the steps in FIG. 7, and some of the operations described below can be replaced oreliminated for additional embodiments of the method 70. The order of theoperations may be interchangeable. Further, the same or similarconfiguration, structure, materials, operations or processes of theforegoing embodiments may be employed in this embodiment and thedetailed explanation may be omitted.

At step 702, a reticle pod is transported to a processing tool and areticle is moved out of the reticle pod. At step 704, a first operationis performed on the reticle for forming a pattern on the reticle. Insome embodiments, the first operation may include one or more of theoperations illustrated in FIGS. 3A to 3L, and may include exposure,development, baking, etching, stripping, or other semiconductorprocessing operations.

At step 706, the reticle is deposited in the reticle pod and the reticlepod is transported to an inspection tool. At step 708, an inspectionoperation is performed on the reticle through a window of the reticlepod. The material and configuration of the window are described withreference to the window 114 in FIG. 1 and FIG. 2B.

At step 710, it is determined during the inspection operation whetherany defect is found. If affirmative, the method 70 proceeds with step712 to determine the defect type. If it is determined at step 710 thatno defect is found in the reticle, the method loops back to step 704 forperforming a subsequent manufacturing step until the reticle iscompleted.

At step 712, it is determined whether the defect type is a contaminationtype or a design type. If it is determined that the detected defect iscategorized as a contamination type, the method 70 proceeds with step714 in which the processing tool is shut down and a cleaning operationis performed on the processing tool for cleaning up the foreignparticles, dust or unreacted gas. The processing tool resumes operationagain if no further contamination is found.

Subsequently, at step 716, a second operation is performed on thereticle for repairing the defect. During step 716, the reticle pod istransported to the processing chamber and the reticle is removed fromthe reticle pod, after which a second operation is performed forrepairing the defect. The second operation may include removal of excessportions or rebuilding of missing portions of one or more layers in thereticle.

In some embodiments, the method 70 accesses a library of reticlepatterns to determine the type of the defect. The library stores relateseveral reticle patterns to identified causes of the defects. Asdiscussed previously, the defects may be caused due to contamination ordesign error. Further, the defective reticle patterns resulting fromcontamination or design error may have specific appearances. The librarymay help identify which type of design error, e.g., bridging, intrusionand protrusion, given the acquired pattern image of the reticle. Thelibrary may improve the efficiency and accuracy of the causes based onthe inspection image of the reticle.

In some embodiments, the method 70 proceeds with step 708 for inspectingthe reticle after the repairing operation at step 716. The method 70 maycycle through the steps 708, 710, 712, 714 and 716 until no defects arefound in the repaired reticle.

If it is determined at step 712 that the detected defect is categorizedas a design type, the method 70 proceeds with step 716 for performingthe second operation. At step 718, it is determined whether thefabrication of the reticle is completed. If affirmative, the method 70is concluded. If one or more operations are required, the method 70loops back to step 704 for performing another first operation until thereticle is completed.

FIG. 8 is a flowchart of a method 80 of manufacturing a semiconductordevice, in accordance with some embodiments. The semiconductor devicemay be manufactured using the reticle 108 that is fabricated, inspected,repaired and operated in related to the reticle pod 10 as described inpreceding paragraphs. The reticle 108 used in method 80 is deemed ascompleted and no defects have been found therein. It is understood thatadditional operations can be provided before, during, and after thesteps in FIG. 8 , and some of the operations described below can bereplaced or eliminated for additional embodiments of the method 80. Theorder of the operations may be interchangeable. Further, the same orsimilar configuration, structure, materials, operations or processes ofthe foregoing embodiments may be employed in this embodiment and thedetailed explanation may be omitted.

The method 80 begins at step 802, wherein a workpiece, such as asemiconductor substrate having a material layer, is provided. Thesemiconductor substrate includes a semiconductor material such assilicon. In some embodiments, the semiconductor substrate may includeother semiconductor materials, such as silicon germanium, siliconcarbide, gallium arsenide, or the like. Alternatively, the semiconductorsubstrate includes another elementary semiconductor, such as germanium;a compound semiconductor including silicon carbide, gallium arsenic,gallium phosphide, indium phosphide, indium arsenide, and/or indiumantimonide; an alloy semiconductor including SiGe, GaAsP, AlInAs,AlGaAs, GaInAs, GaInP, and/or GaInAsP; or combinations thereof. In someembodiments, the semiconductor substrate includes doped regions, such asp-type doped regions or n-type doped regions.

In some embodiments, the material layer of the semiconductor substratemay be a semiconductor layer, a dielectric layer or a conductive layer.In some embodiments, the material layer may be embedded in thesemiconductor substrate or deposited over the semiconductor substrate.The material layer may be formed of a single layer or may include amultilayer structure.

At step 804, a photoresist layer is formed over the material layer. Thephotoresist layer may be formed over the material layer by CVD, PVD,ALD, spin coating, or another suitable film-forming method. Next, themethod 80 continues with step 806, in which the photoresist layer ispatterned using a reticle, such as the reticle 108 described above, in alithography operation. In an embodiment, the reticle may be disposed ona reticle stage of a lithography system and the semiconductor substratemay be disposed on a wafer stage. The lithography operation may involveprojection of an exposure radiation onto the photoresist layer viatransmission or reflection onto the reticle. Portions of the photoresistlayer may be removed after the lithography operation.

The method 80 continues with step 808 to pattern the material layerusing the patterned photoresist layer as an etch mask. Next, thephotoresist layer is removed. The removal operations may include anetching or ashing operation.

According to an embodiment, a method includes: inspecting a reticle in areticle pod, the reticle pod including a sealed space to accommodate thereticle, and the reticle pod further comprising a window arranged on anupper surface of the reticle pod, wherein the inspecting is performedthrough the window; and moving the reticle out of the reticle pod forperforming a lithography operation using the reticle.

According to an embodiment, a method includes: performing a firstoperation for forming a pattern on a reticle in a first processing tool;moving the reticle into a reticle pod and closing the reticle pod; anddetermining whether any defect exists in the reticle by transmitting aradiation through a transparent window of the reticle pod withoutopening the reticle pod.

According to an embodiment, a method includes: performing a firstoperation using a reticle in a first processing tool; enclosing thereticle by a reticle pod, the reticle pod comprising a window allowingthe reticle to be visible through the window; performing an inspectionoperation on the reticle through the window; and determining that adefect is found during the inspection operation before moving thereticle out of the reticle pod.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method comprising: inspecting a reticle in a reticle pod, the reticle pod including a sealed space to accommodate the reticle, and the reticle pod further comprising a window arranged on an upper surface of the reticle pod, wherein the inspecting is performed through the window; and moving the reticle out of the reticle pod for performing a lithography operation using the reticle.
 2. The method of claim 1, further comprising performing a first operation for forming a pattern on the reticle subsequent to the moving of the reticle.
 3. The method of claim 2, further comprising performing a second operation for repairing the pattern on the reticle in response to a defect being found during the inspecting.
 4. The method of claim 2, further comprising performing the lithography operation by transferring the pattern on the reticle to a workpiece in response to no defect being found.
 5. The method of claim 2, wherein the first operation includes a development operation for forming a patterned photoresist layer on the reticle, further comprising: transporting the reticle from the reticle pod to a semiconductor tool subsequent to the inspecting; and causing a foreign particle to be removed from the reticle in response to the foreign particle being detected during the inspecting.
 6. The method of claim 5, further comprising performing a patterning operation using the patterned photoresist layer as an etch mask subsequent to the removal of the foreign particle.
 7. The method of claim 5, further comprising cleaning a processing tool performing the development operation prior to a patterning operation in response to the foreign particle being detected.
 8. The method of claim 2, wherein the first operation includes a development operation for forming a patterned mask layer on the reticle, further comprising: transporting the reticle from the reticle pod to a semiconductor tool subsequent to the inspecting; and repairing a defective portion of the patterned mask layer in response to the defective portion being detected during the inspecting.
 9. The method of claim 8, further comprising performing a patterning operation using the patterned mask layer as an etch mask subsequent to the repairing of the defective portion.
 10. The method of claim 1, wherein the inspecting comprises emitting an inspection radiation to pass through the window and receiving reflected radiation from the reticle.
 11. A method comprising: performing a first operation for forming a pattern on a reticle in a first processing tool; moving the reticle into a reticle pod and closing the reticle pod; and determining whether any defect exists in the reticle by transmitting a radiation through a transparent window of the reticle pod without opening the reticle pod.
 12. The method of claim 11, wherein the radiation has a wavelength so as not to react with a photoresist material of the reticle.
 13. The method of claim 12, wherein the wavelength is in a range between about 400 nm and about 700 nm.
 14. The method of claim 11, wherein the transparent window comprises a window body and a transparent film on two sides of the window body.
 15. The method of claim 14, wherein the transparent film comprises at least one of aluminum zinc oxide (AZO), indium tungsten oxide (ITO), fluorine doped tin oxide (FTO) and carbon nanotube.
 16. The method of claim 14, wherein the transparent film comprises a thickness between about 20 nm and about 200 nm.
 17. The method of claim 14, wherein the reticle pod comprising a cover including an opaque material laterally surrounding the transparent window.
 18. A method comprising: performing a first operation using a reticle in a first processing tool; enclosing the reticle by a reticle pod, the reticle pod comprising a window allowing the reticle to be visible through the window; performing an inspection operation on the reticle through the window; and determining that a defect is found during the inspection operation before moving the reticle out of the reticle pod.
 19. The method of claim 18, wherein the reticle is kept within the reticle pod during the inspection operation.
 20. The method of claim 18, wherein reticle pod further comprises a cover including a film on two sides of the window, wherein the film has a transmittance of greater than about 65% for an inspection radiation used in the inspection operation. 